Abstract:

The low thermal conductivity and poor shape-stability of organic paraffin as phase change material have limited their applications. In order to improve the thermal conductivity and anti-leakage performance of paraffin, wood was modified by chitosan and carbonized at high temperature to prepare hierarchical porous carbon skeleton, which can not only firmly adsorb paraffin but also greatly improve the thermal conductivity of phase change composite (PCC). The morphology, phase change cycling stability, thermal conductivity and photothermal conversion performance were tested. The results show that with the introduction of multi-scaled porous structure, PCCs have good shape-stability without obvious leakage. The phase change enthalpy of the PCC is 126.9 J/g. The phase-transition temperature and enthalpy of the PCC have no obvious change over the 100 cycles of melting and solidification, indicating that the PCC has good cyclic stability. The thermal conductivity of PCC is also greatly improved and presents obvious anisotropic thermal conductivity. The out-of-plane and in-plane thermal conductivity of PCC are 0.67 and 0.41 W/(m·K), respectively. The great improvement of the out-of-plane thermal conductivity is conducive to improve the thermal management application of PCC. In addition, it is also found that PCC has good photothermal conversion performance. The composite phase change materials developed in this paper have application prospects in the fields of heat storage and thermal management.

Key words: composites, biomass porous carbon, phase change thermal storage, heat transfer, solar energy

摘要：

针对石蜡热导率低以及易泄漏等问题，以生物质木头多孔碳作为导热填料骨架，利用壳聚糖改性木头多孔碳在其竖向孔道中生长碳薄片形成分级多孔网络结构，并与石蜡复合制成定形复合相变材料（PCC）。结果表明，由于分级多孔网络骨架的引入，PCC的定形效果好，无明显泄漏，其相变焓值为126.9 J/g，经100次熔化凝固循环测试，其相变温度和焓值均无明显变化，具有良好的循环稳定性。PCC的导热性能具有较大提高，且呈现明显的各向导热异性，平面外和平面内热导率分别为0.67和0.41 W/(m·K)。此外，通过模拟太阳光进行光热实验，发现PCC具有良好的光热转换性能。本复合相变材料在储热以及热管理领域具有应用前景。

关键词: 复合材料, 生物质多孔碳, 相变储热, 传热, 太阳能